Vehicles may use a timing belt or chain to drive various features in an internal combustion engine.
For example, U.S. Pat. No. 4,715,333 describes a camshaft drive arrangement that allows for valve timing adjustment. The system includes a flexible transmitting belt that may engage with a pair of opposing pulleys and a plurality of sprockets as well as a tensioning pulley in order to drive rotating parts with a single belt.
The inventors herein have recognized various issues with the above system. In particular, increasing the number of sprockets and/or pulleys to retain a reflex wrap angle also increases the size and weight of the camshaft drive.
As such, one example approach to address the above issues is to engage the camshaft drive and the crankshaft drive with different, opposing sides of a band, such as a timing belt and/or timing chain. In this way, it is possible to achieve a reflex wrap angle around the sprockets, pulleys and/or additional features engaged with the timing band, while maintaining a compact configuration and package. Specifically, the camshaft engages a first side of the timing band and the crankshaft engages a second, opposite, side of the timing band. This configuration enables the crankshaft to be arranged within a more central location of the engine drive system, if desired, and thus the engine drive system may be arranged in a more compact design. Further, by taking advantage of two sides of the timing band and arranging the crankshaft in a more central location, a reflex wrap angle around the drive sprockets may be achieved without the inclusion of additional sprockets, pulleys, idling devices and/or tensioning devices (although such additional devices can be included, if desired).
Note that various bands may be used, such as timing chain, a timing belt, or various other types of elastic and/or inelastic flexible bands. Further, the band may mate to toothed or un-toothed pulleys on the various shafts. Further still, additional bands may also be used, if desired.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.